Group 22 - Swingline Electric Stapler
Modern technologies have improved rapidly during the last half of the 20th century. Nowadays, engineers have to consider many factors while designing a product. The success of many products are based on the use of advanced technologies in their design and operation. Great products, such as the iPod, with a compact and beautiful design and friendly user interface have enjoyed tremendous popularity in the consumer world.
Our group’s mission was to disassemble a Swingline portable electrical stapler, analyze its design, and attempt to improve the product. Our first impression was that it’s very easy to use. Just press the paper in against the tabs and down comes the staple. With a compact, sleek design, it’s also very eye-catching. It is electrically powered, drawing electricity from one of two sources; an AC adapter that plugs into a standard wall outlet, or six AA batteries. This dual-power source feature gives the product great mobility. A stapler remover, which cleverly fits into the casing, gives users an added bonus.
As we disassembled the stapler, we found that it has a very simple design. When a stack of papers is placed under the staple area, the document presses a metal tab up against a metal plate, instantly closing the circuit. When the circuit is closed, a circuit board sends a signal to the motor. The motor spins, turning a set of four small gears that are connected to it. The last gear has a tab on it, and when the gear spins, the tab presses the stapler arm down against the paper, finally stapling the document. All of this seemingly lengthy process happens within microseconds. The automatic function of the stapler can be disabled by using a manual switch on the left side of the stapler. The user then can trigger the motor to run through a small button on top of stapler.
It was not difficult to disassemble or reassemble the product. It does, however, have many delicate parts that can be easily broken. Many of the parts would be very difficult to replace if broken. As we disassembled it, for instance, a black wire that connected the motor and the circuit board was accidentally pulled off, disabling the entire product. After analyzing the product, we have come up with the following suggestions:
- Better housing of the wires
- Better design for the staple tray to avoid jamming
- More clearance in the staple area, allowing the user to staple larger documents
Our product is a Swingline portable electric stapler ( Model #42130). It runs on one of two power sources; by plugging it into a wall outlet or on six AA batteries. There are two ways the stapler will work; if the stapler is in automatic mode the paper presses a trigger in the back of the staple area which makes the stapler staple the document, if it is in manual mode the user has to press a small button on the top of the stapler. The stapler has an adjustable depth, which changes how far down from the top of the paper the staple in inserted, and comes with a built in staple remover.
Our group consisted of four members:
David Irving: Group leader, in charge of group, worked on the CAD drawing, and oral presenter
Mike Wulff: In charge of the written report and oral presenter
Tuan Nguyen: In charge of the written report and helped with written part of oral presentation
Nick Martin: In charge of disassembly and reassembly of the product
- All members helped on disassembly and reassembly of the product.
Purpose of Product
The purpose of the Swingline Electric Stapler is to provide a way for a user to bind papers together with a staple without requiring any force to be applied by the user.
How it works
When paper is put into the stapler, it presses on a trigger. When the trigger is activated, the stapler arm is pressed down and a staple is driven through the papers. A metal plate under the papers bends the staple to prevent it from unintentionally coming off.
Types of Energy Used
The stapler converts electrical energy (in the form of DC current from a battery or converted from AC current from a wall outlet) to mechanical energy that is used to force the staple through the paper.
Before disassembly, staples were put into the staple tray, and the product was tested. The product ran as expected, stapling a small stack of papers together without problems. As it operated, a blue LED light flashed at the base of the stapler. The plastic casing didn't move at all during operation, just the metal stapler arm. A low noise could be heard, probably coming from motors and gears operating.
Before disassembly, we expected to find about sixty components in total in the stapler. We felt this was a reasonable number because we expected there would be many small parts needed inside the stapler. We expected to find five different materials used to make the various components, with most of the parts being plastic or a type of metal.
All steps easy and required little force unless otherwise noted.
Screwdriver used is regular Phillips screwdriver unless noted. Used to remove all screws.
If no tool mentioned, operation done with hands.
1.Staple remover was removed by pressing on indentation with the symbol and pulling towards the back of the stapler
2.Black casing was removed by pinching at the front and sliding towards the back of the stapler (to completely remove, move to the back as far as it easily goes, then pinch the front of the piece and pull firmly until it comes off)
3.Sticker showing battery positioning was cut with a slot screwdriver
4.Stapler was turned over, and the black padding and white “Swingline” sticker were peeled off
5.Two screws on left hand side of casing removed
6.Six screws on bottom of casing removed
7.Blue staple depth tabs were removed by pulling off
8.Casing was removed by carefully pulling each half (left and right) in opposite directions. Pulled until completely separated, but some slack still in wires
9.Battery contacts removed by sliding out of their slots
10.Screws holding circuit on left side of casing removed
11.Blue manual-auto switch pulled out
12.Manual trigger removed by pulling off support pegs (Needed slot screwdriver to pry trigger off of supports)
13.Casings completely removed and set aside
14.LED bulb casing removed
15.Two screws holding metal gear frame to bottom casing on left side removed
16.Two screws holding metal gear frame to bottom casing on bottom removed
17.Bottom casing removed and set aside
18.Black-and-red and red-and-white-and-black wires running from bottom casing disconnected from circuit board
19.Black-and-red wires running from lower front of stapler removed
20.Main circuit board screw removed
NOTE: single black wire pulled out of socket during next step, making complete reassembly impossible
21.Circuit board removed and wrapped around toward back of stapler
22.Screws holding metal gear casing and plastic gear casing removed
23.Slot screwdriver used to bend lock washer until it could be removed from the last gear shaft
24.Plastic and metal casings separated
25.Shaft at back and spring coil removed
26.Gear casing separated from staple slide
27.Screws holding plastic and metal bottom casings removed, and pieces separated
|Part #||Part Name||Quantity||Purpose||Material and Reason for Choice of Material||Manufacturing|
|1||Spring||1||Holds potential energy||Steel, Needs to be sturdy, but compressible||Extruded, Shaped|
|2||Shaft||12||Supports gears, aligns parts||Steel, Holds shape well under stress||Extruded|
|3||Washer||2||Provides spacing between fasteners and casings||Steel, Holds shape well||Cut|
|4||Lock washer||4||Holds shafts in place||Steel, Less likely to bend when pulled on||Cut|
|5||Casing||4||Shields insides from environment||ABS Plastic, Sturdy, weather resistant||Injection Molded|
|6||Foam Pad||2||Cuts down on noise, holds parts in place||Foam, Suppresses sound and movement||Cut|
|7||Battery Contacts||2||Transfers electrical energy from batteries||ABS Plastic, Steel, Needs to conduct electricity||Injection Molded, Cut|
|8||LED Light||1||Sends visual signals to user||ABS Plastic, Needs to be clear||Injection Molded|
|9||Manual Start Button||1||Can be pressed to eject staple||Plastic, Outside parts need to be weather resistant||Injection Molded|
|10||Staple Remover||1||Can be used to remove unwanted staples||Plastic, Steel, Holds shape well under stress||Injection Molded, Machined|
|11||Staple Tray||1||Stores staples until they are used||Steel, Staples need to slide easily||Machined|
|12||Staple Pusher||1||Ejects staple when pressure applied||Steel, Holds shape well under pressure||Machined|
|13||Steel Gear Casing||1||Holds gears in place||Steel, Can't deform during operation||Machined|
|14||Rivet||1||Holds Staple Pusher to frame||Steel, Holds shape under pressure||Cut|
|15||Gears||6||Transfers kinetic energy from motor to Staple Pusher, changes power of system||Plastic, lightweight||Injection Molding|
|16||Motor Frame||1||Encases motor||Steel, Keeps other parts out of motor||Machined|
|17||Plastic Gear Casing||1||Helps hold gears in place||Plastic, Lightweight but sturdy||Metal Casting|
|18||Rubber Spacer||1||Provides spacing between fasteners and casings||Rubber, Has some elasticity||Cut|
|19||Drive Spacer||1||Helps hold gears in place||Plastic, Lightweight||Injection Molding|
|20||Electric Motor||1||Turns electrical energy to kinetic energy||Steel, Needs to conduct electricity||Machined|
|21||Staple Tray Button||1||Ejects staple tray||ABS Plastic, Outside parts need to be weather resistant||Manufactured|
|22||Frame for Button||1||Holds button in place||Steel, Needs to be held in place during operation||Metal Casting|
|23||Circuit Board||1||Organizes and interprets electrical signals||Silicon, Plastic, Conducts electricity well, won't interfere with circuits||Manufactured|
|24||Ribbon||1||Used to remove batteries||Nylon, Flexible and won't tear when pulled on||Manufactured|
|25||Metal Coil||1||Stores potential energy||Steel, Good elasticity and hold shape||Machined|
|26||Plastic Display||1||Houses LED light||ABS Plastic, Needs to be clear||Injection Molding|
|27||Small Circuit Board||1||Organizes and interprets electrical signals||Plastic, Silicon, Conducts electricity well, won't interfere with circuits||Manufactured|
|28||Plastic Slide||1||Adjusts how far down from top of paper staple will be inserted||ABS Plastic, Outside pieces need to be weather resistant||Injection Molding|
|29||Plastic Housing||2||Protects inside pieces||ABS Plastic, Outside pieces need to be weather resistant||Injection Molding|
|30||Screws||25||holds separate pieces together||Steel, Holds shape well under stress||Machined|
|31||Plastic Ends||2||Used with Plastic Slide||ABS Plastic, Outside pieces need to be weather resistant||Injection Molding|
|32||Rubber Bottom||1||Provides cushion between stapler and surface||Rubber, Won't scratch tabletop||Cut|
|33||Information Sheet||1||Contains Model Name and other info about stapler||Aluminum, Plastic Coated, Can be printed on easily||Manufactured|
|34||Small Plastic Housing||1||Protects inside pieces||Plastic, Outside pieces need to be weather resistant||Injection Molding|
|35||Wires||6||Transfers electrical signals to different parts of stapler||Copper, Rubber, Conducts electricity well, insulates well||Manufactured|
Pictures Of Dissection
|After Step 8|
|After Step 13|
|After Step 19|
|After Step 21|
|After Step 27|
The CAD files can be downloaded here.
We suggest the following changes be made to the product:
- Make wires more secure
We felt the inside workings of the stapler were too delicate. Many of the wires running from the main circuit board to the various parts of the stapler were not attached securely enough. The wires were very thin and could easily be cut or pulled out of their connections if not handled with extreme care. If heavier adhesives or thicker wires were used, this would be less of a problem.
- Change staple tray
The staple tray is easily jammed. It is supported on two rails, one on each side of the tray. When the button is pressed to eject the tray so staples can be loaded, the tray usually gets caught up on its rails. The user then needs to pull on the tray to create enough clearance to load the staples into the tray, and the force needed is usually significant. We suggest polishing the rails and the tray, or using a lubricant, in order to decrease the friction between the rails and the tray and prevent the jamming. The rails and the tray could be manufactured so that the fit between them is more exact, which could also help prevent jamming. If the fit is too loose, there could be too much play between the parts, allowing them to jam, which seems to be the case now. If the fit is too tight, however, the friction between the parts increases, which could also cause it to jam.
- Increase clearance where paper is inserted
Due to the rigidity of the stapler's casing, there is little clearance where the paper is inserted. This prevents the user from stapling large documents. Increasing this clearance would allow more papers to be stapled at once, although it would increase the overall size of the stapler. Also, a stronger motor or different gear ratios might be needed to ensure the stapler has the power to force the staple through a thicker stack of papers.
The assembly procedure is very much the reverse process of the disassembly procedure, and is done mostly by hand, screwdrivers only in use when screws are used to attach components:
1.Gears put back into gear casing
2.Metal and plastic casings put back together and lock washer put back on shaft
3.Circuit board attached back into the plastic casing using 2 screws
Note: the single black wire that connect between the main circuit board and the motor is pulled out, we can’t fixed it due to lack of proper tools
5.Black-red wires running from lower front of stapler attached back to the main circuit board
6.Black-red and red-white-black wires running from bottom casing are attached back to the main circuit board
7.Bottom casing attached back to the whole metal casing using 4 screws, 2 on the left side, 2 on the right side
8.LED bulb attached back to the plastic casing
9.Blue manual-auto switch attached between the metal casing and the bottom plastic casing.
10.Battery contacts attached back to the main black casing
11.Two plastic casing pieces put back together
12.Plastic casing pieces attached back to the bottom plastic casing using 6 screws
13.Blue staple depth tabs attached
14.The “Swingline” sticker attached back to the bottom
15.The staple remover attached back to its original slot
How Product Works
- In Automatic mode
As stated in Executive Summary:
When a stack of papers is placed under the staple area, the document presses a metal trigger up against a metal plate, instantly closing the circuit. When the circuit is closed, a circuit board sends a signal to the motor. The motor spins, turning a set of four small gears that are connected to it. The last gear has a tab on it, and when the gear spins, the tab presses the stapler arm down against the paper, finally stapling the document.
- In Manual mode
When paper is inserted in the staple area, the user presses a small button on the top of the stapler. This button has a plastic tab on the bottom of it (inside the stapler when fully assembled). The tab presses a metal trigger against a metal plate, closing the circuit. This mechanism is same as in the automatic process, but it is in a different place in the stapler using different physical parts. The rest of the process is same as above.
Product Operation After Reassembly
The product did not run the same as before disassembly due to a technical difficulty. The housing for the wire within the stapler was pretty fragile. During the disassembly process, we accidentally pull a black wire that connected the main circuit board and the motor, making operation imposible. We can’t fix this problem due to technically difficulty caused by lack of proper tools.
Product Testing Possibilities
The most important part to research would be in the area of how many papers the stapler could staple. This number would have to be quite accurate because it would most likely be used while advertising the product. The following is a possible mathmatical model:
The first step would be to determine how much power is needed to punch through a piece of paper. From there a motor and gear assembly with the proper ratios to match the amount of power needed can be designed. When this is done the size of the staple can be chosen to match the power of the motor. The motor may be able to punch through 40 papers but if the staple can not reach that far it can't be said that the stapler will work on 40 papers.
Comparison of Disassembly and Assembly Processes
The disassembly and assembly processes are pretty much the reverse of one another. Some of the steps within the processes can be switched, but the general big steps are just the reverse of each other. Because it’s basic principles that you take some thing off, you just have to put the back the same way (e.g. you unscrew a screw on one slot by turning the screw counterclockwise, then when you put it back, you will turn the screw clockwise). We use the same set of tools to assemble and disassemble the product. We were not able to assemble of the product due to lack of proper tools (to fix the black wire that connects the main circuit board and the motor).
Additional Suggested Changes
NOTE: see also After Disassembly
- Better housing of the wire. The wire connecting to the motor should be held in place by a clamp. Other exposed wires should be held in place by tape so that they are not loose and easily pulled.
- Better design for the stapler slide to avoid jamming. If the release button was able to push down farther it wouldn’t catch the staple tray causing it to stop short of being fully extended. Also if the spring used had more resistance it would provide a stronger force when ejecting the staple tray.
- The outer casing should be altered so that it does not cover the staple tray. This would give the consumer easy access to the tray so that he/she can see why the tray is jammed.
- The clearance of the stapler should be raised so it can staple bigger documents, which means the addition of a stronger motor.
- The current design uses 5 gears. If this number was reduced to three gears more space would be available for a larger motor. This would also reduce the amount of energy lost due to friction between the gears, which makes better use of the motors power.
(2006). Swingline. Retrieved December 3, 2007.
Web site: http://www.acco.com/swingline/